Wednesday, September 4, 2013

Intro to Phil Matich and bull sharks in the Everglades

Hi everyone.  My name is Phil Matich and I’m currently a PhD student in the Heithaus Lab.  I started working with the lab as a volunteer at our field site in Shark Bay, WA in 2008, and after arriving in Miami, I immediately started working on my research in the Shark River Estuary in the Florida Everglades.  My project has focused on understanding what factors shape juvenile bull shark behavior and how predicted changes in the environment will affect their ecological roles.  Over the last five years I have been catching, tagging and tracking sharks using passive acoustic telemetry to investigate individual differences in movement patterns and the degree of plasticity among shark movements within the nursery, and I have been collecting tissue samples from sharks to investigate dietary patterns using stable isotope analysis.  Thus far we’ve found that bull sharks, like other predators in the ecosystem, can exhibit a high degree of individual variation in their behavior.  For example, some sharks have more specialized diets and prefer marine or estuarine taxa, while others are more generalized in their trophic interactions.  Also, some sharks make repeated movements between refuge and foraging areas, while others tend to just roam around.  My current research aims to quantify the effects of an extreme cold weather event, that occurred in 2010, on the shark nursery, and we’re finding that changes in abundance and competition among age-classes may be leading to more rapid ontogenetic shifts in habitat use and diet.  Since this cold snap event, we’ve caught 60 juvenile bull sharks in the estuary, and have acoustically tagged 36 individuals to track their movements, of which 27 sharks are still in the estuary and providing us with an abundance of movement data that we download and evaluate every 2-4 months.  Over the next few years we should begin to understand the long-term effects of this event on the nursery.  Thanks for reading, stay tuned for future posts on fieldwork, manuscripts and other exciting news.

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